Oil pressure questions

[OldMan89]

Ok I don’t mean to be repetitive on the forum but I’ve read a ton on here that the factory oil pressure gauge in the dash of my ‘89 is basically a go/no go gauge. No problem. Got that. But hear me out lol I’ve had the truck for about a year and a half. Drive it every day. About a month into having it the needle started to move from the dead center (between the R and M) to between the O and R… that’s when I found out they are kind of a dumb gauge. Then 6 months in the needle moved to between the N and O…. I figure it’s still reading so nothing can be wrong. Then about a week ago it just started to float randomly from dead center to just below the N…. Is this normal and just going to be annoying or can I change the sensor to the gauge? Should I investigate more things?? I have about 1000 miles in this oil change.

 

[rusty ol ranger]

Ok I don’t mean to be repetitive on the forum but I’ve read a ton on here that the factory oil pressure gauge in the dash of my ‘89 is basically a go/no go gauge. No problem. Got that. But hear me out lol I’ve had the truck for about a year and a half. Drive it every day. About a month into having it the needle started to move from the dead center (between the R and M) to between the O and R… that’s when I found out they are kind of a dumb gauge. Then 6 months in the needle moved to between the N and O…. I figure it’s still reading so nothing can be wrong. Then about a week ago it just started to float randomly from dead center to just below the N…. Is this normal and just going to be annoying or can I change the sensor to the gauge? Should I investigate more things?? I have about 1000 miles in this oil change.

Pull the wire off the sender and ground it out, see if the gauge goes all the way up (key on), if it does then your wireing/gauge is fine...and you need a sender.

If it dont go all the way up then its a wireing/gauge issue.

These gauges are on or off. If they read inbetween its a sender and/or wire issue.

 

[scotts90ranger]

Sometime during the turbo swap process my '90 did similar, it's been down about 1/4 way up since then but I have a manual gauge and it has a ton of oil pressure (25psi hot idle and 50psi hot cruise...).

It's probably just a bad connection somewhere

 

[RonD]

Yes, 1989 should use an Oil Pressure Switch on the engine, 5.5psi rating
So below 5.5psi the switch is open, not grounded, gauge shows no pressure
Above 5.5psi it is closed, grounded, gauge shows in normal range

When gauge in dash is grounded by the switch it reads in the Normal range, via a resistor on the back of the cluster
Any changes in the needles position would be electrical not pressure related

So the switch on the engine may have a fault or poor ground on its threads
Or wire connections to the gauge may have corrosion
Or your alternator is failing causing fluctuations in voltage in the vehicles electric system, i,e, flickering lights?
And could be the gauge itself is faulty, low odds but not 0, lol

If you ground the Sender wire and turn on the key gauge should only go to normal range not High, grounding the wire is the same thing switch does.


You can convert gauge to "real oil pressure" by using a PS60(or similar) Sender on the engine and then by-passing the resistor on the back of the cluster
The resistor was moved to INSIDE the gauge in the mid-1990's so can't be by-pass after that
1989 would for sure have the exposed resistor

Article here on doing this conversion: https://www.therangerstation.com/tech/variable-oil-pressure-gauge-modification/

 

[OldMan89]

Pull the wire off the sender and ground it out, see if the gauge goes all the way up (key on), if it does then your wireing/gauge is fine...and you need a sender.

If it dont go all the way up then its a wireing/gauge issue.

These gauges are on or off. If they read inbetween its a sender and/or wire issue.

Thank you. I will try this!!

 

[OldMan89]

Yes, 1989 should use an Oil Pressure Switch on the engine, 5.5psi rating
So below 5.5psi the switch is open, not grounded, gauge shows no pressure
Above 5.5psi it is closed, grounded, gauge shows in normal range

When gauge in dash is grounded by the switch it reads in the Normal range, via a resistor on the back of the cluster
Any changes in the needles position would be electrical not pressure related

So the switch on the engine may have a fault or poor ground on its threads
Or wire connections to the gauge may have corrosion
Or your alternator is failing causing fluctuations in voltage in the vehicles electric system, i,e, flickering lights?
And could be the gauge itself is faulty, low odds but not 0, lol

If you ground the Sender wire and turn on the key gauge should only go to normal range not High, grounding the wire is the same thing switch does.


You can convert gauge to "real oil pressure" by using a PS60(or similar) Sender on the engine and then by-passing the resistor on the back of the cluster
The resistor was moved to INSIDE the gauge in the mid-1990's so can't be by-pass after that
1989 would for sure have the exposed resistor

Article here on doing this conversion: https://www.therangerstation.com/tech/variable-oil-pressure-gauge-modification/

Thanks so much!! I’m going to look into this!!

 

[RonD]

On 1989-1992 cluster, seen here: https://i.ebayimg.com/images/g/gngAAOSwHRViucAR/s-l1600.jpg

I think the resistor to by pass is what the hands index finger is pointed at.....................I think